Control circuit for air fan heaters



July 28, 1953 M. E. LAUTNER 2,647,198

CONTROL CIRCUIT FOR AIR FAN HEATERS Filed March 10, 1951 Patented July28, 1953 UNITED STATES ?ATENT OFFICE CONTROL CIRCUIT FOR AIR FAN HEATERSApplication'March 10, 1951, Serial No. 214,899

3 Ciaima, (01. 219-39) This invention relates to a control circuit foran electric circulating fan having heating means for the air and inwhich selective control is had for heating the air or not as desired.

One object of the invention is to provide a comparatively simplearrangement for reducing the speed of the fan when the heating elementis energized so that most eiiici'ent pick-up of heatfrom the heatingelement by the air being circulated. is had, yet when the air is beingcirculated without being heated, the fan may operate at relatively highspeed for producing the desired circulation.

Another object is to provide a high speed fan for normal air circulationand a means to slow down its speed when. the air is being heated byelectric heating elements.

A further object is to provide a control switch and circuit arrangementfor a heating element and a fan motor to accomplish the desired resultswithout the use of a separate potentiometer or rheos-tat portions of theheating elementitself being utilized for effecting the desired controlor different speed of the motor when the air is heated compared to whenit is not heated.

Still a further object is to provide a circuit arrangement having asingle control switch which opens both sides of the line in the offposition of the switch.

With these and other objects in view, my in vention consists in theconstruction, arrangement and combination of the various parts of mycontrol circuit for air fan heater, whereby the objects contemplated areattained, as hereinafter more fully set forth, pointed out in my claimsand illustrated in the accompanying drawings, wherein:

Figure 1 is a rear elevation of an air fan heater of the generalcharacter shown in my copending application, Serial No. 216,168, filedMarch 17, 1951, and including a control circuit in accordance with thepresent invention.

Figure 2 is an electrodiagrammatic view of the control circuit with theswitch in the off position.

Figure 3 is a similar view showing the switch in position forenergization of the fan without heating the air.

Figure 4 is a similar view with the switch in position for operating thefan and heating the air.

Figure 5 is a view for tracing out the circuit of Figure 3; and

Figure 6 is a similar view for tracing out the circuit of Figure 4.

On the accompanying drawing I have used the reference numeral H) toindicate a supporting base and I2 a U-shaped supporting strap for atubular casing I4- The casing l4 has supported therein a circular wiret6 provided with suitable means of attachment to the casing andsupporting amotor i8. A fan blade 20 is mounted on the shaft of the:motor for circulating the air through the casing ['4 when the motor isenergized.

Heating element supports 22, 24 and 26 extend. inwardly from thecircular wire [.6 for supporting a heating element comprising sections38, 4'0, 42 and 44. Terminals 28 and 30 are supported on and insulatedfrom the support 22, and terminals 32 and 34" are supported on andinsulated from the support 24. A shunt 36 connects the terminals 32 and34 and suitable wiring connects the terminals 28 and 30 with a switch S.

The circuit. connections are shown diagrammatically in Figures 2 1:06.In Figure 2, the switch 3 is in the on? position so that none of theheating element sections nor the motor [8 are energized, and both sidesof the line are open.

In Figure 3, the motor I8 is energized but one section 44 of the.heating element is in series. therewith and this can be traced outsomewhat better in Figure 5 from line L to line L The motor [8 drawsabout one-half ampere of current and the resistance of the heatingelement section 44 is only two or three ohms. This gives only about onevolt drop across the heating element section 44 which acts as aresistance, volts being applied across the line L L Accordingly, themotor operates at substantially line voltage and the half ampere ofcurrent flowing through the resistance 44 hardly affects it so that itdoes not act as a heating element but merely as a resistance.

When both the fan and the heating element are on, the switch S ispositioned as in Figure 4 giving a circuit arrangement such as shown inFigure 6 with the heating element sections 38, 4D and 42 in series withthe heating element section 44 across the line and the three sections38, 40 and 42 are then in parallel with the motor l8. This results inabout three-fourths of the line voltage across the motor and its speedis therefore considerably reduced.

Thus a high speed motor is had for efficient air circulation when it isdesirable that room air be circulated but not heated. When it isdesirable to heat the air, the heating element comes into full scaleoperation utilizing all four sections 38, 40, 42 and 44 but due to thepeculiar connection of the section 44 in the circuit in relation to themotor, the motor is slowed down considerably so as to slowly circulatethe air over the heating element to permit maximum pick-up of heattherefrom and accordingly slow enough circulation of the air that it iscirculated as hot air and not as merely slightly warmed air.

With the arrangement disclosed, a unique control of the circuit is hadfor securing high and low speed operation of the fan as desired from asingle switch and utilizing the heating element efiiciently forslow-down of the fan when the heating element is energized, yetpermitting it to operate at substantially maximum speed without heatingthe air in the circuit position of Figures 3 and 5 even though part ofthe heating element is used in the circuit at that time. My experiencehas been that the heat generated by the section 44 is relativelynegligible during cool air circulation because of the high resistance ofthe motor windings yet the normal arrangement of a heating element and afan both energized for circulating hot air is had with a slowing down ofthe fan as desirable when the heating element is energized. The singleswitch provided also disconnects all electrical elements of theappliance from either side of the supply line when the switch isadjusted to the off position.

Some changes may be made in the construction and arrangement of theparts of my control circuit for air fan heater without departing fromthe real spirit and purpose of my invention, and it is my intention tocover by my claims any modified forms of structure or use of mechanicalequivalents which may be reasonably included within their scope.

I claim as my invention:

1. In a control circuit for an air fan heater adapted to be suppliedwith electric current from a supply line, an air circulating fan, aheating element having two sections, a switch for energizing said fanfor circulating either room air or heated room air, said switch in oneposition connecting said fan in series with one section of said heatingelement, in another position effecting a similar connection andconnection of the other section of the heating element in series withsaid one section and in parallel with said fan motor, and in stillanother position disconnecting both said fan and said heating elementfrom both sides of the supply line.

2. A control circuit for an air fan heater adapted to be energized froma pair of line wires comprising an air circulating fan, a heatingelement for heating air circulated thereby, and a threeposition switchfor controlling said fan and heating element by selectively connecting aminimum portion of said heating element in series with the fan for highspeed operation of the fan when the switch is in a first position, alsoconnecting a major portion of the heating element in parallel with thefan when the switch is in a second position for low speed operation ofthe fan when heating the air circulated thereby, and disconnecting thefan and heating element from both of the line wires when the switch isin a third position.

3. A control circuit for a two wire electrically energizable air fanheater comprising a threeblade, three-position switch having fivecontacts, said blades being connected to the two supply wires and saidcontacts being connected to the fan and a heating element forcontrolling them by selectively connecting a minimum portion of theheating element in series with the fan for high speed operation of thefan in one position of said blades, connecting a major portion of theheating element in parallel with the fan and in series with said minimumportion of the heating element for low speed operation of the fan whenheating the air circulated thereby in another position of said blades ordisconnecting both line wires from the fan and heater in still anotherposition of said blades.

MAX E. LAUTNER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,450,589 Graft" et al Apr. 3, 1923 2,149,689 Smith et a1 Mar.7, 1939 2,509,137 Denman Mar. 23, 1950

